In co-pending application, Ser. No. 07/343,447, filed on Apr. 26, 1989, now U.S. Pat. No. 5,048,809,--the contents of which are expressly incorporated herein by this reference--and assigned to the same assignee as the instant application, there is described document folding apparatus utilizing glue dispensing means. In general, the apparatus described in the co-pending application is characterized by a plurality of fold plates radiating, as spokes from a central part--the hub--where a plurality of rollers are clustered to sequentially feed documents to a succession of fold plates at which successive folds are imposed on the document. Glue dispensing apparatus is disposed on at least one of the fold plates to apply glue to one of the edges of the folded document so that when a subsequent fold is accomplished, the document gets folded onto a glued edge and thereby sealed.
When a plurality of folds is imposed on a document along one of its dimensions, it is apparent that the document will "shrink" with each successive fold. Thus, as the document is successively conveyed from the hub to a fold plate, back again to the hub, and subsequently to another fold plate, the distance that the document will travel along each successive fold plate will likewise "shrink" in a fashion analagous to that of an Archimedes Spiral. That is, the radial distance from the hub at which each subsequent folding operation occurs, decreases. The effect of this shrinkage is a tendency to concentrate successive stages of folding apparatus closer to the hub where the space availability for the apparatus becomes increasingly limited. In particular, where gluing apparatus is preferably used only in the last stage of folding apparatus, the space available for such gluing apparatus has become quite limited, especially where a plurality of folds have been imposed on a document.
Accordingly, it is a primary object of this invention to provide a glue dispensing apparatus having a physical profile adapted to the limited space availability in the latter stages of document folding apparatus having a plurality of fold plates.
As described in the aforementioned copending application, the glue dispensing apparatus disclosed therein preferably comprises, in one embodiment thereof, a glue distributing manifold to which are attached a plurality of pressure responsive glue dispensing nozzles. Solenoids mounted on top of the manifold move the manifold into engagement with a folded document to deposit a plurality of spots of glue onto one of the edges of a document. Apparatus featuring top mounted solenoids has been on sale by the assignee of this application for more than one year preceeding the filing date of this application and this feature thereby constitutes prior art against this application.
Solenoids mounted on top of a glue distributing manifold increase the profile of glue dispensing apparatus and limit the placement thereof to only those spaces capable of accomodating such profile.
Accordingly, it is another object of this invention to provide a solenoid actuated glue dispensing apparatus in which the solenoids are not mounted on top of the glue distributing manifold. The profile of such apparatus is thus decreased and thus allows placement of the apparatus in more restricted space environments.
The inherent characteristics of glues causes them to harden when exposed to air. Despite the use of pressure responsive nozzles which dispense glue only upon contact--thus sealing the glue in the nozzles from contact with air at all other times--it is inevitable that the nozzles will accumulate hardened glue deposits over a period of time of successive actuations. At such times the nozzles have to be cleaned.
Accordingly, it is yet another object of the invention to provide a manifold and nozzle assembly that can be easily detached from the glue dispensing apparatus so that the nozzles can be cleaned and freed from hardened glue deposits.
In addition to dealing with the above noted "shrinkage" of documents as they undergo successive folding operations, document folding and gluing apparatus also has to accomodate varying initial sizes of documents. Both of these demands require that any glue dispensing apparatus be adjustable.
Accordingly, it is a still further object of this invention to provide glue dispensing apparatus that can easily be adjusted to accomodate a variety of document sizes, whether in their initial stage, or any subsequent stage of the folding operation.
It is also clear that the thickness of a folded document will vary as the number of folds thereof varies. Any glue dispensing apparatus therefore which moves an assembly of pressure responsive glue dispensing nozzles into engagement with such folded documents has to be able to acccomodate such varying thickness.
It is therefore yet another object of the invention to provide glue dispensing apparatus which can easily be adjusted to accomodate a document of varying thickness.
Once adjustments, including the aforementioned ones, have been made to any document folding and gluing apparatus, the physical distances are normally fixed. However, a major adjustment remains, namely cycle speed. That is, the folding and gluing apparatus can be set to operate at cycle speeds which can, in the extreme, range from about one hundred documents per hour to ten thousand per hour. Thus, while the physical distances will not change during any given run of identical parameters, the time consumed in traversing those distances surely will.
Thus, it is still another object of the invention to provide gluing apparatus which can be adjusted to actuate glue dispensing nozzles at varying times within the variable cycle speed of the folding and gluing apparatus.